lib/libkvm/kvm.c

   1 /*-
   2  * Copyright (c) 1989, 1992, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software developed by the Computer Systems
   6  * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
   7  * BG 91-66 and contributed to Berkeley.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * @(#)kvm.c    8.2 (Berkeley) 2/13/94
  38  * $FreeBSD: src/lib/libkvm/kvm.c,v 1.12.2.3 2002/09/13 14:53:43 nectar Exp $
  39  * $DragonFly: src/lib/libkvm/kvm.c,v 1.10 2007/04/29 01:36:04 dillon Exp $
  40  */
  41
  42 #include <sys/user.h>   /* MUST BE FIRST */
  43 #include <sys/param.h>
  44 #include <sys/proc.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/stat.h>
  47 #include <sys/sysctl.h>
  48 #include <sys/linker.h>
  49
  50 #include <vm/vm.h>
  51 #include <vm/vm_param.h>
  52 #include <vm/swap_pager.h>
  53
  54 #include <machine/vmparam.h>
  55
  56 #include <ctype.h>
  57 #include <fcntl.h>
  58 #include <kvm.h>
  59 #include <limits.h>
  60 #include <nlist.h>
  61 #include <paths.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <stdarg.h>
  66 #include <unistd.h>
  67
  68 #include "kvm_private.h"
  69
  70 /* from src/lib/libc/gen/nlist.c */
  71 int __fdnlist           (int, struct nlist *);
  72
  73 char *
  74 kvm_geterr(kvm_t *kd)
  75 {
  76         return (kd->errbuf);
  77 }
  78
  79 /*
  80  * Report an error using printf style arguments.  "program" is kd->program
  81  * on hard errors, and 0 on soft errors, so that under sun error emulation,
  82  * only hard errors are printed out (otherwise, programs like gdb will
  83  * generate tons of error messages when trying to access bogus pointers).
  84  */
  85 void
  86 _kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
  87 {
  88         va_list ap;
  89
  90         va_start(ap, fmt);
  91         if (program != NULL) {
  92                 (void)fprintf(stderr, "%s: ", program);
  93                 (void)vfprintf(stderr, fmt, ap);
  94                 (void)fputc('\n', stderr);
  95         } else
  96                 (void)vsnprintf(kd->errbuf,
  97                     sizeof(kd->errbuf), (char *)fmt, ap);
  98
  99         va_end(ap);
 100 }
 101
 102 void
 103 _kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
 104 {
 105         va_list ap;
 106         int n;
 107
 108         va_start(ap, fmt);
 109         if (program != NULL) {
 110                 (void)fprintf(stderr, "%s: ", program);
 111                 (void)vfprintf(stderr, fmt, ap);
 112                 (void)fprintf(stderr, ": %s\n", strerror(errno));
 113         } else {
 114                 char *cp = kd->errbuf;
 115
 116                 (void)vsnprintf(cp, sizeof(kd->errbuf), (char *)fmt, ap);
 117                 n = strlen(cp);
 118                 (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
 119                     strerror(errno));
 120         }
 121         va_end(ap);
 122 }
 123
 124 void *
 125 _kvm_malloc(kvm_t *kd, size_t n)
 126 {
 127         void *p;
 128
 129         if ((p = calloc(n, sizeof(char))) == NULL)
 130                 _kvm_err(kd, kd->program, "can't allocate %u bytes: %s",
 131                          n, strerror(errno));
 132         return (p);
 133 }
 134
 135 static kvm_t *
 136 _kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
 137 {
 138         struct stat st;
 139
 140         kd->vmfd = -1;
 141         kd->pmfd = -1;
 142         kd->nlfd = -1;
 143         kd->vmst = 0;
 144         kd->procbase = NULL;
 145         kd->procend = NULL;
 146         kd->argspc = 0;
 147         kd->argv = 0;
 148
 149         if (uf == 0)
 150                 uf = getbootfile();
 151         else if (strlen(uf) >= MAXPATHLEN) {
 152                 _kvm_err(kd, kd->program, "exec file name too long");
 153                 goto failed;
 154         }
 155         if (flag & ~O_RDWR) {
 156                 _kvm_err(kd, kd->program, "bad flags arg");
 157                 goto failed;
 158         }
 159         if (mf == 0)
 160                 mf = _PATH_MEM;
 161
 162         if ((kd->pmfd = open(mf, flag, 0)) < 0) {
 163                 _kvm_syserr(kd, kd->program, "%s", mf);
 164                 goto failed;
 165         }
 166         if (fstat(kd->pmfd, &st) < 0) {
 167                 _kvm_syserr(kd, kd->program, "%s", mf);
 168                 goto failed;
 169         }
 170         if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
 171                 _kvm_syserr(kd, kd->program, "%s", mf);
 172                 goto failed;
 173         }
 174         if (S_ISCHR(st.st_mode)) {
 175                 /*
 176                  * If this is a character special device, then check that
 177                  * it's /dev/mem.  If so, open kmem too.  (Maybe we should
 178                  * make it work for either /dev/mem or /dev/kmem -- in either
 179                  * case you're working with a live kernel.)
 180                  */
 181                 if (strcmp(mf, _PATH_DEVNULL) == 0) {
 182                         kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
 183                 } else if (strcmp(mf, _PATH_MEM) != 0) {
 184                         _kvm_err(kd, kd->program,
 185                                  "%s: not physical memory device", mf);
 186                         goto failed;
 187                 } else {
 188                         if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
 189                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 190                                 goto failed;
 191                         }
 192                         if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
 193                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 194                                 goto failed;
 195                         }
 196                 }
 197         } else {
 198                 /*
 199                  * This is a crash dump.
 200                  * Initialize the virtual address translation machinery,
 201                  * but first setup the namelist fd.
 202                  */
 203                 if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
 204                         _kvm_syserr(kd, kd->program, "%s", uf);
 205                         goto failed;
 206                 }
 207                 if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
 208                         _kvm_syserr(kd, kd->program, "%s", uf);
 209                         goto failed;
 210                 }
 211                 if (_kvm_initvtop(kd) < 0)
 212                         goto failed;
 213         }
 214         return (kd);
 215 failed:
 216         /*
 217          * Copy out the error if doing sane error semantics.
 218          */
 219         if (errout != 0)
 220                 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
 221         (void)kvm_close(kd);
 222         return (0);
 223 }
 224
 225 kvm_t *
 226 kvm_openfiles(const char *uf, const char *mf, const char *sf, int flag,
 227               char *errout)
 228 {
 229         kvm_t *kd;
 230
 231         if ((kd = malloc(sizeof(*kd))) == NULL) {
 232                 (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
 233                 return (0);
 234         }
 235         memset(kd, 0, sizeof(*kd));
 236         kd->program = 0;
 237         return (_kvm_open(kd, uf, mf, flag, errout));
 238 }
 239
 240 kvm_t *
 241 kvm_open(const char *uf, const char *mf, const char *sf, int flag,
 242          const char *errstr)
 243 {
 244         kvm_t *kd;
 245
 246         if ((kd = malloc(sizeof(*kd))) == NULL) {
 247                 if (errstr != NULL)
 248                         (void)fprintf(stderr, "%s: %s\n",
 249                                       errstr, strerror(errno));
 250                 return (0);
 251         }
 252         memset(kd, 0, sizeof(*kd));
 253         kd->program = errstr;
 254         return (_kvm_open(kd, uf, mf, flag, NULL));
 255 }
 256
 257 int
 258 kvm_close(kvm_t *kd)
 259 {
 260         int error = 0;
 261
 262         if (kd->pmfd >= 0)
 263                 error |= close(kd->pmfd);
 264         if (kd->vmfd >= 0)
 265                 error |= close(kd->vmfd);
 266         if (kd->nlfd >= 0)
 267                 error |= close(kd->nlfd);
 268         if (kd->vmst)
 269                 _kvm_freevtop(kd);
 270         if (kd->procbase != NULL)
 271                 free(kd->procbase);
 272         if (kd->argv != 0)
 273                 free((void *)kd->argv);
 274         free((void *)kd);
 275
 276         return (0);
 277 }
 278
 279 int
 280 kvm_nlist(kvm_t *kd, struct nlist *nl)
 281 {
 282         struct nlist *p;
 283         int nvalid;
 284         struct kld_sym_lookup lookup;
 285
 286         /*
 287          * If we can't use the kld symbol lookup, revert to the
 288          * slow library call.
 289          */
 290         if (!ISALIVE(kd))
 291                 return (__fdnlist(kd->nlfd, nl));
 292
 293         /*
 294          * We can use the kld lookup syscall.  Go through each nlist entry
 295          * and look it up with a kldsym(2) syscall.
 296          */
 297         nvalid = 0;
 298         for (p = nl; p->n_name && p->n_name[0]; ++p) {
 299                 lookup.version = sizeof(lookup);
 300                 lookup.symname = p->n_name;
 301                 lookup.symvalue = 0;
 302                 lookup.symsize = 0;
 303
 304                 if (lookup.symname[0] == '_')
 305                         lookup.symname++;
 306
 307                 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
 308                         p->n_type = N_TEXT;
 309                         p->n_other = 0;
 310                         p->n_desc = 0;
 311                         p->n_value = lookup.symvalue;
 312                         ++nvalid;
 313                         /* lookup.symsize */
 314                 }
 315         }
 316         /*
 317          * Return the number of entries that weren't found.
 318          */
 319         return ((p - nl) - nvalid);
 320 }
 321
 322 ssize_t
 323 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
 324 {
 325         int cc;
 326         void *cp;
 327
 328         if (ISALIVE(kd)) {
 329                 /*
 330                  * We're using /dev/kmem.  Just read straight from the
 331                  * device and let the active kernel do the address translation.
 332                  */
 333                 errno = 0;
 334                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 335                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 336                         return (-1);
 337                 }
 338
 339                 /*
 340                  * Try to pre-fault the user memory to reduce instances of
 341                  * races within the kernel.  XXX workaround for kernel bug
 342                  * where kernel does a sanity check, but user faults during
 343                  * the copy can block and race against another kernel entity
 344                  * unmapping the memory in question.
 345                  */
 346                 bzero(buf, len);
 347                 cc = read(kd->vmfd, buf, len);
 348                 if (cc < 0) {
 349                         _kvm_syserr(kd, 0, "kvm_read");
 350                         return (-1);
 351                 } else if (cc < len)
 352                         _kvm_err(kd, kd->program, "short read");
 353                 return (cc);
 354         } else {
 355                 cp = buf;
 356                 while (len > 0) {
 357                         u_long pa;
 358
 359                         cc = _kvm_kvatop(kd, kva, &pa);
 360                         if (cc == 0)
 361                                 return (-1);
 362                         if (cc > len)
 363                                 cc = len;
 364                         errno = 0;
 365                         if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 366                                 _kvm_syserr(kd, 0, _PATH_MEM);
 367                                 break;
 368                         }
 369                         bzero(cp, cc);
 370                         cc = read(kd->pmfd, cp, cc);
 371                         if (cc < 0) {
 372                                 _kvm_syserr(kd, kd->program, "kvm_read");
 373                                 break;
 374                         }
 375                         /*
 376                          * If kvm_kvatop returns a bogus value or our core
 377                          * file is truncated, we might wind up seeking beyond
 378                          * the end of the core file in which case the read will
 379                          * return 0 (EOF).
 380                          */
 381                         if (cc == 0)
 382                                 break;
 383                         cp = (char *)cp + cc;
 384                         kva += cc;
 385                         len -= cc;
 386                 }
 387                 return ((char *)cp - (char *)buf);
 388         }
 389         /* NOTREACHED */
 390 }
 391
 392 char *
 393 kvm_readstr(kvm_t *kd, u_long kva, char *buf, size_t *lenp)
 394 {
 395         size_t len, cc, pos;
 396         char ch;
 397         int asize = -1;
 398
 399         if (buf == NULL) {
 400                 asize = len = 16;
 401                 buf = malloc(len);
 402                 if (buf == NULL) {
 403                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 404                         return NULL;
 405                 }
 406         } else {
 407                 len = *lenp;
 408         }
 409
 410         if (ISALIVE(kd)) {
 411                 /*
 412                  * We're using /dev/kmem.  Just read straight from the
 413                  * device and let the active kernel do the address translation.
 414                  */
 415                 errno = 0;
 416                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 417                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 418                         return NULL;
 419                 }
 420
 421                 for (pos = 0, ch = -1; ch != 0; pos++) {
 422                         cc = read(kd->vmfd, &ch, 1);
 423                         if ((ssize_t)cc < 0) {
 424                                 _kvm_syserr(kd, 0, "kvm_readstr");
 425                                 return NULL;
 426                         } else if (cc < 1)
 427                                 _kvm_err(kd, kd->program, "short read");
 428                         if (pos == asize) {
 429                                 buf = realloc(buf, asize *= 2);
 430                                 if (buf == NULL) {
 431                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 432                                         return NULL;
 433                                 }
 434                                 len = asize;
 435                         }
 436                         if (pos < len)
 437                                 buf[pos] = ch;
 438                 }
 439
 440                 if (lenp != NULL)
 441                         *lenp = pos;
 442                 if (pos > len)
 443                         return NULL;
 444                 else
 445                         return buf;
 446         } else {
 447                 size_t left = 0;
 448                 for (pos = 0, ch = -1; ch != 0; pos++, left--, kva++) {
 449                         if (left == 0) {
 450                                 u_long pa;
 451
 452                                 left = _kvm_kvatop(kd, kva, &pa);
 453                                 if (left == 0)
 454                                         return NULL;
 455                                 errno = 0;
 456                                 if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 457                                         _kvm_syserr(kd, 0, _PATH_MEM);
 458                                         return NULL;
 459                                 }
 460                         }
 461                         cc = read(kd->vmfd, &ch, 1);
 462                         if ((ssize_t)cc < 0) {
 463                                 _kvm_syserr(kd, 0, "kvm_readstr");
 464                                 return NULL;
 465                         } else if (cc < 1)
 466                                 _kvm_err(kd, kd->program, "short read");
 467                         if (pos == asize) {
 468                                 buf = realloc(buf, asize *= 2);
 469                                 if (buf == NULL) {
 470                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 471                                         return NULL;
 472                                 }
 473                                 len = asize;
 474                         }
 475                         if (pos < len)
 476                                 buf[pos] = ch;
 477                 }
 478
 479                 if (lenp != NULL)
 480                         *lenp = pos;
 481                 if (pos > len)
 482                         return NULL;
 483                 else
 484                         return buf;
 485         }
 486         /* NOTREACHED */
 487 }
 488
 489 ssize_t
 490 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
 491 {
 492         int cc;
 493
 494         if (ISALIVE(kd)) {
 495                 /*
 496                  * Just like kvm_read, only we write.
 497                  */
 498                 errno = 0;
 499                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 500                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 501                         return (-1);
 502                 }
 503                 cc = write(kd->vmfd, buf, len);
 504                 if (cc < 0) {
 505                         _kvm_syserr(kd, 0, "kvm_write");
 506                         return (-1);
 507                 } else if (cc < len)
 508                         _kvm_err(kd, kd->program, "short write");
 509                 return (cc);
 510         } else {
 511                 _kvm_err(kd, kd->program,
 512                     "kvm_write not implemented for dead kernels");
 513                 return (-1);
 514         }
 515         /* NOTREACHED */
 516 }